N-Haloalkyl thiobenzanilides and their use as fungicides

ABSTRACT

N-haloalkyl thiobenzanilide compounds having the formula ##STR1## in which R is hydrogen, C 1  -C 5  alkyl, preferably C 1  -C 3  alkyl, C 1  -C 3  haloalkyl, preferably --CF 3 , halogen including --F, --Cl, --Br, and --I, --NO 2 , C 1  -C 2  alkoxy and X and Y are either --C1 or --F but not identical and their use as fungicides.

This invention relates to certain novel N-haloalkyl thiobenzanilideswhich are useful as fungicides.

The compounds of the present invention correspond to the formula##STR2## in which R is hydrogen, C₁ -C₅ alkyl, preferably C₁ -C₃ alkyl,C₁ -C₃ haloalkyl, preferably --CF₃, halogen including --F, --Cl, --Br,and --I, --NO₂, C₁ to C₂ alkoxy and X and Y are either --Cl or --F butnot identical.

Although the compounds of the invention are generally active asfungicides, it has been discovered that they are also effective assystemic toxicants and this ancillary feature greatly increases theirusefulness and versatility in treating fungus-infected food crops. Asthose skilled in the art are aware, a systemic biocide is taken upinternally by the organism to which it is applied and lodges in thetissues while still retaining toxicological properties. When used toprotect food crops systemic toxicants are not subject to weatheringsince they are confined within the interstices of the plant tissueswhich are thereby internally immunized against the attack of harmfulfungi, blights and similar pesticidal microorganisms.

The compounds of the present invention are prepared by the followinggeneral reaction. ##STR3##

Generally a molar amount of the substituted benzoyl chloride reactant,dissolved in benzene, is added to a mixture of the aniline reactant anda slight molar excess of an HCl acceptor such as triethylamine. Themixture is refluxed for 1/2 hour and then cooled. The solid reactionproduct is diluted with a solvent such as ethyl acetate or chloroformand washed with water twice and salt solution once. The final product isdried over MgSO₄, filtered and evaporated. ##STR4##

Under a dry nitrogen atmosphere a molar amount of the reaction productfrom Reaction No. 1 is dissolved in dry tetrahydrofuran (THF). Next, aslight molar excess of NaH is added with stirring. The mixture isrefluxed for 1 hour and cooled. ##STR5##

A molar amount of ##STR6## in THF is added dropwise to the reactionmixture of Reaction No. 2. The mixture is refluxed for 21/2 hours and alarge amount of CH₂ Cl₂ is added to the solid reaction product. Theproduct is washed twice with water, dried over MgSO₄ and evaporated.##STR7## An equimolar mixture of Reagent I and Reagent II is irradiatedunder a U V lamp (at 8° C. to 60° C.) for 3 to 5 hours. The product IIIis isolated and purified by distillation under reduced pressure (40 mmHg to 50 mm Hg).

Preparation of compounds of this invention is illustrated by thefollowing examples.

EXAMPLE I Preparation of 2-iodobenzoyl anilide ##STR8##

43.2 g. (0.464 moles) aniline and 46.9 g. triethylamine are mixed in 930ml. benzene by stirring. A solution of 123.7 g. (0.464 moles)2-iodobenzoyl chloride in 450 ml. benzene is added to the first mixturethrough a dropping funnel. An exothermic reaction takes place. After theaddition is finished, the mixture is refluxed for 1/2 hour. The mixtureis cooled and the product solidifies. The product is filtered, added towater, and stirred to dissolve triethylamine hydrochloride. The productis filtered again and dried to yield 146.8 g. of the desired product.(98% yield) m.p. 141°-144° C.

EXAMPLE II ##STR9##

8.075 g. (0.025 moles) of the amide reaction product of Example I isdissolved in 60 ml. of dry THF under a dry nitrogen atmosphere. 0.66 g.(0.0275 moles) NaH is added to the mixture with stirring. The mixture isrefluxed for one hour and then cooled.

EXAMPLE III N-1,1,2-trichloro-2,2-difluoromethylthio-o-iodobenzanilide##STR10##

(0.025 moles) of ClSCCl₂ CF₂ Cl dissolved in 12 ml. THF is addeddropwise to the cooled reaction mixture of Example II. The mixture isthen refluxed for 21/2 hours. Next 150 ml. CH₂ Cl₂ is added, the mixtureis washed twice with water, dried over MgSO₄ and evaporated to yield thedesired product.

The following is a table of certain selected compounds that arepreparable according to the procedure described herein. Compound numbersare assigned to each compound and are used throughout the remainder ofthe application.

                  TABLE I    ______________________________________     ##STR11##    Compound                       Physical Constants    Number    R        X       Y   m.p. or n.sub.D.sup.30    ______________________________________    1         2-I      Cl      F   glassy solid    2         H        Cl      F   semi-solid    3         H        F       Cl  1.5772    4         2-CF.sub.3                       F       Cl  1.5345    5         2-CF.sub.3                       Cl      F   1.5410    6         2-I      F       Cl  1.6034    7         2-OCH.sub.3                       F       Cl  1.5698    ______________________________________

Foliar Fungicide Evaluation Tests A. Evaluation for Preventive Action

1. Bean Rust Test:

Pinto bean plants (Phaseolus vulgaris L.) approximately 10 centimeters(cm.) tall are transplanted into sandy loam soil in three-inch claypots. The plants are then inverted and dipped for two to three secondsin 50--50 acetone/water solution of the test chemical. Testconcentrations range from 1000 ppm downward. After the leaves are dried,they are inoculated with a water suspension of spores of the bean rustfungus (Urumyces phaseoli Arthur) and the plants are placed in anenvironment of 100% humidity for 24 hours. The plants are then removedfrom the humidity chamber and held until disease pustules appear on theleaves. Effectiveness is recorded as the lowest concentration, in ppm,which will provide 75% or greater reduction in pustule formation ascompared to untreated, inoculated plants. These values are recorded inTable II.

2. Bean Powdery Mildew Test:

A candidate chemical is prepared and applied in the same manner as forthe bean rust test. After the plants are dry, the leaves are dusted withspores of the powder mildew fungus (Erysiphe polygoni De Candolle) andthe plants are retained in the greenhouse until the fungal growthappears on the leaf surface. Effectiveness is recorded as the lowestconcentration, in ppm, which will provide 75% or greater reduction inmycelial formation as compared to untreated, inoculated plants. Thesevalues are recorded in Table II.

3. Tomato Early Blight:

A candidate compound is dissolved in an appropriate solvent and dilutedwith a 50--50 acetone water solution. Four week old tomato (Lycopersiconesculentum) plants are then sprayed with the solution to the point ofrunoff. Test concentrations range from 1000 ppm downward. When theleaves are dry, they are inoculated with a water suspension of spores ofthe early blight fungus (Alternaria solani Ellis and Martin) and placedin an environment of 100% humidity for 48 hours. The plants are thenremoved from the humidity chamber and held until disease lesions appearon the leaves. Effectiveness is recorded as the lowest concentration, inppm, which will provide 75% or greater reduction in the number oflesions formed as compared to untreated, inoculated plants. These valuesare recorded in Table II.

4. Blue Grass Leaf Spot:

A candidate chemical is prepared and applied in the same manner as thetomato early blight test except that four week old Kentucky Bluegrass(Poa pratensis) plants are utilized as the host plant. When the leavesare dry, they are inoculated with a water suspension of spores of theblue grass leaf spot fungus (Helminthosporium sativum) and placed in anenvironment of 100% humidity for 48 hours. The plants are then removedfrom the humidity chamber and held until disease lesions appear on theleaves. Effectiveness is recorded as the lowest concentration, in ppm,which will provide 75% or greater reduction in number of lesions formedas compared to untreated, inoculated plants. These values are recordedin Table II.

B. Evaluation for Eradicant Action

1. Bean Rust Test:

Untreated bean plants (Phaseolus vulgaris L.) are inoculated with sporesof the bean rust fungus (Uromyces phaseoli Arthur) and placed in anenvironment with 100% humidity for 24 hours. The plants are then removedfrom the humidity chamber and held in the greenhouse for two days toallow the disease to become established. A candidate chemical is thenprepared and applied in the same manner as in the bean rust test in"Evaluation for Preventive Action". Eradicative effectiveness isrecorded as the lowest concentration, in ppm, which will provide a 75%or greater reduction in number of pustules appearing on the leaves ascompared to untreated inoculated plants. These values are recorded inTable II.

2. Bean Powdery Mildew Test:

Untreated pinto bean plants are dusted with spores of the powdery mildewfungus (Erysiphe polygoni De Candolle) and maintained in the greenhouseuntil mycelial growth appears in the leaf surface. A candidate chemicalis then prepared and applied in the same manner as for the bean rusttest. Four days later the leaves are examined for inhibition of furthermycelial growth. Eradicative effectiveness is recorded as the lowestconcentration, in ppm, which will provide a 75% or greater inhibition ofviable, sporulating mycelium as compared to untreated inoculated plants.These values are recorded in Table II.

                  TABLE II    ______________________________________    Preventive Action    Compound            Bean   Bean Powdery                               Tomato Early                                         Blue Grass    Number  Rust   Mildew      Blight    Leaf Spot    ______________________________________    1       10     100         100       25    2       25      50         50        25    3       50      50         25        25    4       25     100         50        50    5       10     100         50        100    6       10     100         50        *    7       50      50         50        100    ______________________________________     *No control at 1000 ppm and not tested at higher concentrations.

    Eradicant Action    1       1      >50    2       >50    >50    3       >50    >50    4       0.5     50    5       0.5    (50)    6       0.5    >50    7       --     --    ______________________________________     () Indicates partial control.

The compounds of this invention are generally embodied into a formsuitable for convenient application. For example, the compound can beembodied into a pesticidal composition which is provided in the form ofemulsions, suspensions, solutions, dusts and aerosol sprays. In general,such compositions will contain, in addition to the active compound, theadjuvants which are found normally in pesticide preparations. In thesecompositions, the active compound of this invention can be employed asthe sole pesticide component or it can be used in admixture with othercompounds having similar utility. The pesticide compositions of thisinvention can contain, as adjuvants, organic solvents, such as sesameoil, xylene range solvents, heavy petroleum, etc.; water; emulsifyingagents; surface active agents; talc; pyrophyllite; diatomite; gypsum;clays, propellants, such as dichlorodifluoromethane, etc. If desired,however, the active compound can be applied directly to feedstuffs,seeds, etc., upon which the pests feed. When applied in such a manner,it will be advantageous to use a compound which is not volatile. Inconnection with the activity of the presently disclosed pesticidalcompound, it should be fully understood that it is not necessary thatthey be active as such. The purposes of this invention will be fullyserved if the compound is rendered active by external influences, suchas light or by some physiological action which occurs when the compoundis ingested into the body of the pest.

The precise manner in which the pesticidal compositions of thisinvention are used in any particular instance will be readily apparentto a person skilled in the art. Generally, the active pesticide compoundwill be embodied in the form of a liquid composition; for example, anemulsion, suspension, or aerosol spray. While the concentration of theactive pesticide in the present compositions can vary within rather widelimits, ordinarily the pesticide compound will comprise not more thanabout 15.0% by weight of the composition. Preferably, however, thepesticide compositions of this invention will be in the form ofsolutions or suspensions containing about 0.1 to 1.0% by weight of theactive pesticide compound.

What is claimed is:
 1. A compound having the formula ##STR12## .
 2. A method of controlling fungi comprising applying thereto a fungicidally effective amount of a compound having the formula ##STR13## .
 3. A fungicidal composition of matter comprising a fungicidally effective amount of a compound having the formula ##STR14## and an inert diluent carrier. 